Interactive input systems that allow users to inject input (e.g. digital ink, mouse events, etc.) into an application program using an active pointer (e.g. a pointer that emits light, sound or other signal), a passive pointer (e.g. a finger, cylinder or other object) or other suitable input device such as for example, a mouse or trackball, are well known. These interactive input systems include but are not limited to: touch systems comprising touch panels employing analog resistive or machine vision technology to register pointer input such as those disclosed in U.S. Pat. Nos. 5,448,263; 6,141,000; 6,337,681; 6,747,636; 6,803,906; 7,232,986; 7,236,162; and 7,274,356 and in U.S. Patent Application Publication No. 2004/0179001 assigned to SMART Technologies ULC of Calgary, Alberta, Canada, assignee of the subject application, the contents of which are incorporated by reference; touch systems comprising touch panels employing electromagnetic, capacitive, acoustic or other technologies to register pointer input; tablet personal computers (PCs); laptop PCs; personal digital assistants (PDAs); and other similar devices.
When using an interactive input system in a teaching or presentation environment, it is common to mount the touch panel on a wall surface or to support the touch panel on a stand or the like and use a projector to project a computer-generated image onto the touch surface of the touch panel. Often, the touch panel is fixed in position at a height to accommodate users of an average height. This of course can create ergonomic problems as tall users must hunch over to use the touch panel and short users must stretch to use the touch panel. Hunching over for extended periods of time can result in back problems and stretching for extending periods of time can lead to shoulder problems. Providing the ability to adjust the vertical height of the touch panel helps to solve these problems and also allows the touch panel to be used by users of significantly different heights as is commonly the case in school environments where both the teacher and young students need to interact with the touch panel. As will be appreciated, upper regions of the touch panel are simply out of reach of most young students when the touch panel is positioned to facilitate use by the teacher. Although allowing the touch panel to move vertically to accommodate users of different height helps, problems exist in that each time the touch panel is moved, the projector image must be re-aligned with the touch panel. Projectors that include adjustable lens assemblies to enable the projected image to track movement of the touch panel are extremely expensive and as a result have proven to be simply unsuitable.
An interactive input system comprising a touch panel and a boom supporting a projector at one end that are integrated to form a single assembly, has been considered. In this interactive input system, when the vertical height of the touch panel is adjusted, the boom moves with the touch panel thereby to maintain alignment of the projector image with the touch panel. Although this interactive input system addresses the alignment issue noted above, the integrated touch panel and boom assembly is mechanically complex making it expensive. Also, an expensive short throw projector is required in order to minimize the size of the boom. In environments where cost is of primary concern such as in teaching environments, this type of interactive input system has also proven to be unsatisfactory. Furthermore, in environments such as primary schools where the touch panel needs to be lowered significantly to accommodate very small users, the boom may be lowered to a position where it poses a hazard to teachers and other taller users.
The publication entitled “Automatic Projector Calibration with Embedded Light Sensors” authored by Lee et al. (UIST October 2004, Santa Fe, N. Mex.) discloses a calibration system comprising a projector, a set of light sensors embedded in the target surface of a projection screen and a computer for sending pre-warped images to the projector. A sequence of structured light patterns is projected over the projection screen that allows each sensor to discover its location. This sensor location data is reported to the computer which in turn pre-warps the image data conveyed to the projector so that the projected image corresponds with the projection screen. Although this reference discloses a technique for adjusting a projected image so that it fits onto a projection screen there exists a need to improve interactive input/projection systems.
It is therefore an object of the present invention to provide novel image projection methods and interactive input/projection systems employing the same.